This conspiracy theory emerged in the U.S. in the 1960s. The John Birch Society, who asserted that a United Nations force would soon arrive in black helicopters to bring the U.S. under UN control, originally promoted it.[4] The theory re-emerged in the 1990s, under the presidency of Bill Clinton, and has been promoted by talk show host Glenn Beck.[5][6] A similar theory concerning so-called "phantom helicopters" appeared in the UK in the 1970s.[7]

Also known as SLAP (Secret Large-scale Atmospheric Program), this theory alleges that water condensation trails ("contrails") from aircraft consist of chemical or biological agents, or contain a supposedly toxic mix of aluminum, strontium and barium,[8] under secret government policies. An estimated 17% of people globally believe the theory to be true or partly true. In 2016, the Carnegie Institution for Science published the first-ever peer-reviewed study of the chemtrail theory; 76 out of 77 participating atmospheric chemists and geochemists stated that they had seen no evidence to support the chemtrail theory, or stated that chemtrail theorists rely on poor sampling.[9][10]

The disappearance of Malaysia Airlines Flight 370 in southeast Asia in March 2014 has prompted many theories. One theory suggests that this plane was hidden away and reintroduced as Flight MH17 later the same year in order to be shot down over Ukraine for political purposes. Prolific American conspiracy theorist James H. Fetzer has placed responsibility for the disappearance with Israeli Prime Minister Benjamin Netanyahu.[11] Theories have also related to allegations that a certain autopilot technology was secretly fitted to the aircraft.[12]

Malaysia Airlines Flight 17 was shot down over Ukraine by Russia-backed rebels or by the Russian military in July 2014. This event has spawned numerous alternative theories. These variously include allegations that it was secretly Flight MH370, that the plane was actually shot down by the Ukrainian Air Force to frame Russia, that it was part of a conspiracy to conceal the "truth" about HIV (seven disease specialists were on board), or that the Illuminati or Israel was responsible.[11][13]

Multiple conspiracy theories pertain to a fatal oil-rig industrial accident in 2010 in the Gulf of Mexico, alleging sabotage by those seeking to promote environmentalism, or a strike by North Korean or Russian submarines. Elements of such theories have been suggested or promoted by US radio host Rush Limbaugh.[14][15]

A theory claims that The Coca-Cola Company intentionally changed to an inferior formula with New Coke, with the intent either of driving up demand for the original product or permitting the reintroduction of the original with a new formula using cheaper ingredients.[16] Coca-Cola president Donald Keough rebutted this charge: "The truth is, we're not that dumb, and we're not that smart."[17]

Conspiracy theories frequently emerge following the deaths of prominent leaders and public figures. In ancient times, widespread conspiracy theories were circulated pertaining to the death of the Roman emperor Nero, who committed suicide in 68 AD.[18] Some of these theories claimed that Nero had actually faked his death and was secretly still alive, but in hiding, plotting to return and reestablish his reign.[18] In most of these stories, he was said to have fled to the East, where he was still loved and admired.[18] Other theories held that Nero really was dead, but that he would return from the dead to retake his throne.[18] Many early Christians believed in these conspiracy theories and feared Nero's return because Nero had viciously persecuted them.[18] The Book of Revelation alludes to the conspiracy theories surrounding Nero's alleged return in its description of the slaughtered head returned to life.[18]

Also popular are theories about the deaths of celebrities or politicians. Notable among such theories include the long-running "Paul is dead" theory, which alleges that Paul McCartney died in 1966 and was replaced by a look-alike.[32]. Another is the conspiracy theory that widely circulated in Nigeria and alleges that Nigerian president Muhammadu Buhari has died in 2017 and replaced by a lookalike Sudanese impostor. [33][34]

The disappearance, and often presumed death, of an individual may also become a cause for conspiracy theorists. Theories of a cover-up surrounding the 1974 disappearance of Lord Lucan following the murder of his family's nanny include, for example, allegations of a suicide plot whereby his body was fed to tigers at Howletts Zoo.[40][41][42]

Numerous persistent conspiracy theories have also attended the 2007 disappearance of English girl Madeleine McCann.[43]

The Discordian hoax has resulted in one of the world's foremost conspiracy theories, which claims that the "Illuminati" are secretly promoting the posited New World Order. Theorists believe that a wide range of musicians, including Beyoncé and Whitney Houston, have been associated with the "group".[55] Prominent theorists include Mark Dice and David Icke.[56]

Some theorists believe that Denver International Airport stands above an underground city which serves as a headquarters of the New World Order. Theorists cite the airport's unusually large size, its distance from Denver city center, as well as assorted alleged Masonic or Satanic symbols, and a set of murals which include depictions of war and death.[57]

Hungarian-American investor George Soros has been the subject of conspiracy theories since the 1990s. Soros has used his wealth to promote various political, social, educational and scientific causes, grants totaling an estimated $11 billion up to 2016. However, theories tend to assert that Soros is in control of a large portion of the world's wealth and governments, and that he secretly funds a large range of persons and organizations for nefarious purposes, such as Antifa, which the conspiracies allege to be a single far-left militant group. Such ideas have been promoted by Donald Trump,[58]Bill O'Reilly, Roy Moore, Alex Jones, Arizona Congressman Paul Gosar, Breitbart News and cartoonist Ben Garrison. Soros conspiracy theories are sometimes linked to antisemitic conspiracy theories.[59]

One instance of promoting the "mastermind" conspiracy theory occurred in February 2017, when then-Ankara Mayor Melih Gökçek claimed that earthquakes in the western province of Çanakkale could have been organized by dark external powers aiming to destroy Turkey's economy with an "artificial earthquake" near Istanbul.[68] In another example, in November 2017, the Islamist newspaper Yeni Akit claimed that the fashion trend of "ripped denim" jeans was in fact a means of communication, via specific forms of rips and holes, between agents of foreign states and their collaborators in Turkey.[69]

Conspiracy theories concerning Malala Yousafzai are widespread in Pakistan, elements of which originate from a 2013 satirical piece in Dawn. These theories variously allege that she is a Western spy, or that her attempted murder by the Taliban in 2012 was a secret operation to further discredit the Taliban, and was organized by her father and the CIA and carried out by actor Robert de Niro disguised as an Uzbekhomeopath.[74][75][76][77]

Iran's Baha'i minority has been the target of conspiracy theories alleging involvement with hostile powers. Iranian government officials and others have claimed that Bahá'ís have been agents variously of Russian imperialism, British colonialism, American expansionism and Zionism.[98] An apocryphal and historically-inaccurate book published in Iran, entitled The Memoirs of Count Dolgoruki, details a theory that the Bahá'ís intend to destroy Islam. Such anti-Bahá'í accusations have been dismissed as having no factual foundation.[99][100][101]

Pope John Paul I died in September 1978, only a month after his election to the papacy. The timing of his death and the Vatican's alleged difficulties with ceremonial and legal death procedures has fostered several conspiracy theories.

The elderly Pope Benedict XVI's resignation in February 2013, for given reasons of a "lack of strength of mind and body",[116] prompted theories in Italian publications such as La Repubblica and Panorama that he resigned in order to avoid an alleged scandal involving an underground gay Catholic network.[117][118]

"War against Islam" is a conspiracy theory in Islamist discourse which describes an alleged plot to either harm or annihilate the social system within Islam. The perpetrators of this conspiracy are alleged to be non-Muslims and "false Muslims", allegedly in collusion with political actors in the Western world. The "War against Islam" theory is often used in order to refer to modern social problems and changes, but the Crusades are often seen as its starting point.[125]

Among the foremost concerns of conspiracy theorists are questions of alien life; for example, allegations of government cover-ups of the supposed Roswell UFO incident or activity at Area 51.[147] Also popular are theories concerning so-called 'men in black', who allegedly silence witnesses.

Many reports of dead cattle found with absent body parts and seemingly drained of blood have emerged worldwide since at least the 1960s. This phenomenon has spawned theories variously concerning aliens and secret government or military experiments.[148] Prominent among such theorists is Linda Moulton Howe, author of Alien Harvest (1989).[149][150]

In the modern era, political conspiracy theories are often spread using fake news on social media. A 2017 study of fake news published by the Shorenstein Center found that "misinformation is currently predominantly a pathology of the right".[155]

Political conspiracy theories may take generalized and wide-ranging forms concerning wars and international bodies, but may also be seen at a localized level, such as the conspiracy theory pertaining to the 118th Battalion, a British regiment stationed in Kitchener, Ontario during World War I, which is believed by some in Kitchener to still be present and controlling local politics.[156]

Conspiracy theories concerning the Illuminati, a short-lived 18th-century Enlightenment society, appear to have originated in the late 19th century, when some conservatives in Europe came to believe that the group had been responsible for the French Revolution of 1789–1799.[157] Hoaxes about the Illuminati were later spread in the 1960s by a group of American practical jokers known as the Discordians, who, for example, wrote a series of fake letters about the Illuminati to Playboy.[158]

False flag operations are covert operations designed to appear as if they are being carried out by other entities. Some allegations of false flag operations have been verified or have been subjects of legitimate historical dispute (such as the 1933 Reichstag arson attack).[159] Discussions of unsubstantiated allegations of such operations feature strongly in conspiracy theory discourse.

The multiple attacks made on the US by terrorists using hijacked aircraft on 11 September 2001 have proved especially attractive to conspiracy theorists. Theories may include reference to missile or hologram technology. By far, the most popular theory is that the attacks were in fact controlled demolitions,[166][167] a theory which has been rejected by the engineering profession[168] and the 9/11 Commission.

Former US President Obama has been the subject of numerous conspiracy theories. His presidency was the subject of a 2009 film, The Obama Deception, by Alex Jones, which alleged that Obama's administration was a puppet government for a wealthy elite. Another theory which came to prominence in 2009 (known as "birtherism") denies the legitimacy of Obama's presidency by claiming that he was not born in the US.[183] This theory has persisted despite the evidence of his Hawaiian birth certificate and of contemporary birth announcements in two Hawaiian newspapers in 1961.[184] Notable promoters of the theory are dentist-lawyer Orly Taitz[4] and President Donald Trump, who has since publicly acknowledged its falsity but is said to continue to advocate for it privately.[185][186][187] Other theories claim that Obama, a Protestant Christian, is secretly a Muslim.

The United States' Federal Emergency Management Agency is the subject of many theories, including the allegation that the organization has been engaged in the building of concentration camps on US soil, in advance of the imposition of martial law and genocide.[191]

Members of South Africa's African National Congress party have long propagated conspiracy theories, frequently concerning the CIA and alleged white supremacists. In 2014, Deputy Minister of Defence Kebby Maphatsoe joined others in accusing without evidence Public Protector Thuli Madonsela of being a US agent working to create a puppet government in South Africa.[192][193][194]

Occasionally used as a neutral term to denote a nation's bureaucracy,[198] the conspiratorial notion of a "deep state" is a concept originating principally in Middle Eastern and North African politics with some basis in truth, and has been known in the US since the 1960s. It has since come to prominence under the Trump presidency.[199][200] "Deep state" in the latter sense refers to an unidentified "power elite" who act in co-ordinated manipulation of a nation's politics and government. Proponents of such theories have included Canadian author Peter Dale Scott, who has promoted the idea in the US since at least the 1990s, as well as Breitbart News, Infowars and US President Donald Trump.[201] A 2017 poll by ABC News and The Washington Post indicated that 48% of Americans believe in the existence of a conspiratorial "deep state" in the US.[202][203]

A 2013 study approved by the University of Chicago suggested that almost half of Americans believe at least one medical conspiracy theory, with 37% believing that the Food and Drug Administration deliberately suppresses 'natural' cures due to influence from the pharmaceutical industry.[208] A prominent proponent of comparable conspiracy theories has been convicted fraudster Kevin Trudeau.

Water fluoridation is the controlled addition of fluoride to a public water supply to reduce tooth decay.[215] Although many dental-health organizations support such fluoridation, the practice is opposed by conspiracy theorists.[216] Allegations may include claims that it has been a way to dispose of industrial waste,[217][218] or that it exists to obscure a failure to provide dental care to the poor.[216] A further theory promoted by the John Birch Society in the 1960s described fluoridation as a communist plot to weaken the American population.[219]

Vaccine conspiracy theories have been widespread in Nigeria since at least 2003, as well as in Pakistan. Such theories may feature claims that vaccines are part of a secret anti-Islam plot, and have been linked to fatal mass shootings and bombings at vaccine clinics in both countries.[229][230][231]

Genuine American research in the 1950s and 1960s into chemical interrogation and mind-control techniques has prompted many subsequent conspiracy theories, especially following CIA Director Richard Helm's 1973 order to destroy all files related to the project. These theories include the allegation that the mass fatality at Jonestown in 1978 was connected to an MKUltra experiment.[245]

Radio frequency identification chips (RFID), such as are implanted into pets as a means of tracking, have drawn the interest of conspiracy theorists who posit that this technology is secretly in widespread use on humans. Former Whitby town councilor Simon Parkes has promoted this theory, which may be related to conspiracy theories concerning vaccination, electronic banking and the Antichrist.[246][247]

Flat Earth theory first emerged in 19th-century England, despite the Earth's spherical nature having been known since at least the time of Pythagoras. It has in recent years been promoted by American software consultant Mark Sargent through the use of YouTube videos.[248] Flat-earther conspiracy theorists hold that planet Earth is not a sphere, and that evidence has been faked or suppressed to hide the fact that is instead a disc, or a single infinite plane. The conspiracy often implicates NASA. Other claims may include such allegations as that GPS devices are rigged to make aircraft pilots wrongly believe they are flying around a globe.[249][250]

Numerous theories pertain to the alleged suppression of certain technologies and energies. Such theories may focus on the Vril Society Conspiracy, allegations of the suppression of the electric car by fossil-fuel companies (as detailed in the 2006 documentary Who Killed the Electric Car?), and the Phoebus cartel, set up in 1924, which has been accused of suppressing longer-lasting light bulbs.[251] Other long-standing allegations include the suppression of perpetual motion and cold fusion technology by government agencies, special interest groups, or fraudulent inventors.[252]

Conspiracy theorists claim that government agents are utilizing electromagnetic weapons to induce auditory hallucinations on the population. Theorists often cite research into psychotronic weapons,[259] the Cuban Health Attacks, and the Microwave Auditory Effect as proof of their theory. There are over 10,000 people who identify as Targeted Individuals.[260]

Some theories claim that the dates of historical events have been deliberately distorted. These include the phantom time hypothesis of German conspiracy theorist Heribert Illig, who in 1991 published an allegation that 297 years had been added to the calendar by establishment figures such as Pope Sylvester II in order to position themselves at the millennium.

A comparable theory, known as the New Chronology, is most closely associated with Russian theorist Anatoly Fomenko. Fomenko holds that history is many centuries shorter than is widely believed and that numerous historical documents have been fabricated, and legitimate documents destroyed, for political ends. Adherents of such ideas have included chess grandmaster Garry Kasparov.[261]

Conspiracy theorists have long posited a plot by organizations such as NASA to conceal the existence of a large planet in the Solar System known as Nibiru or Planet X, which allegedly, will one day pass close enough to the Earth to destroy it. Predictions for the date of destruction have included 2003, 2012 and 2017. The theory began to develop following the publication of The 12th Planet (1976), by discredited Russian-American author Zecharia Sitchin, was given its full form by Nancy Lieder, and has since been promoted by American conspiracy theorist and End Times theorist David Meade.[265] The notion has remained popular, and received renewed attention during the period prior to the solar eclipse of 21 August 2017.[266][267][268] Other conspiracy theorists in 2017 also predicted Nibiru would appear, including Terral Croft and YouTube pastor Paul Begley.[269][270]

The "frozen envelope theory" suggests that the National Basketball Association rigged its 1985 draft Lottery so that Patrick Ewing would join the New York Knicks. Theorists claim that a lottery envelope was chilled so that it could be identified by touch.[274] A similar "hot balls theory", promoted by Scottish football manager David Moyes, suggests that certain balls used in draws for UEFA competitions have been warmed to achieve specific outcomes.[275]

The 1984 Pepsi 400 at Daytona, Florida, was the first NASCAR race to be attended by a sitting US President, Ronald Reagan, and was driver Richard Petty's 200th victory. Rival driver Cale Yarborough's premature retirement to the pit road has prompted conspiracy theorists to allege that organizers fixed the race in order to receive good publicity for the event.[276]

On the day of the 1998 World Cup Final, Brazilian striker Ronaldo suffered a convulsive fit.[277] Ronaldo was initially removed from the starting lineup 72 minutes before the match, with the teamsheet released to a stunned world media, before he was reinstated by the Brazil coach shortly before kick off.[278][279] Ronaldo "sleepwalked" through the final, with France winning the game.[279] The nature of the incident set off a trail of questions and allegations which persisted for years, with Alex Bellos writing in The Guardian, "When Ronaldo's health scare was revealed after the match, the situation's unique circumstances lent itself to fabulous conspiracy theories. Here was the world's most famous sportsman, about to take part in the most important match of his career, when he suddenly, inexplicably, fell ill. Was it stress, epilepsy, or had he been drugged?".[280] Questions also circulated into who made Ronaldo play the game. The Brazil coach insisted he had the final say, but much speculation focused on sportswear company Nike, Brazil's multimillion-dollar sponsor—whom many Brazilians thought had too much control—putting pressure on the striker to play against medical advice.[280]

^Berkowitz, Bill (2003), "Reframing the Enemy: 'Cultural Marxism', a Conspiracy Theory with an Anti-Semitic Twist, Is Being Pushed by Much of the American Right." Intelligence Report. Southern Poverty Law Center, Summer. "Archived copy". Archived from the original on 7 February 2004. Retrieved 7 February 2004.CS1 maint: Archived copy as title (link)